Electrical switch



Aug. 2, 1927.`

W F WELLS ELECTRICAL SWITCH Filed March 8. 1926 v "I nl, n

Patented Aug. 2p, c1927.

PATENT oFF-ICE.

A WILLIAM FRANKLIN WELLS, or CHICAGO, ILLINOIS.

ELIECTRICAL SWITCH.

Application ledifarch 8, 1928. Serial No. 93,116.

This invention relates to improvements in electrical switches land it consists in the matters hereinafter described and more particularly pointed out in the ap endedv claims.

The primary object of t e resent invention is to provide a simple andJ eilicient electrical snap' switch ofthe quick acting makeand-break type which is positive in operation and reduces arcing to a minimum.

A further object of the invention is to provide a quick make-and-break switdh which must be manually held in its circuit makin position, thus rendering it especially adapte for use in electrically drivenv hand tools and machines.

Still another object of the invention is to provide a switch of the kind specified which comprises but few parts, of a rugged construction and which may be easily assembled and will not readily get out of order.

These objects of the invention, as well as others, to ether with the many advantages thereof will more fully appear as I proceed with my s ecification.

In the rawings:

Fig. 1 is a longitudinal vertical section through one form of switch embodying my invention with the parts thereof in the pos1- tion they occupy w en contact is broken.

Fig. 2 is a view similar to Fig. 1 but with the parts in the position they occupy when contact is made.

Fig. 3 is a top plan view of the same with the parts in the position shown in Fig. 1.

Fig. 4 is a detail view of a modified form of contact members capable of being embodied in my improved switch. A

My improved switch includes a rectangular box-shaped casing 1, which is open at its ends and at its rear, comprises side walls -2 2 and a front wall 3. The lower portions of the side and front walls of the casing areV lined with a suitable sheet of insulating material 4 as best shown in Figs. 2 and 3. Thek reater portion of the open rear of the cas- 1n is closed by a block of insulation 5 suitably secured in position by pins 6 extending kthrough the same and throu h portions of the side walls. In said insulation block 5 are fixed spaced contacts Tand 8, each provided with a binding'screw 7 and 8, respectively,

at. the rear of the casing for the attachment of the circuit wires to be controlled but npt shown herein. Said contacts -as shown 1n 'notch or recess 11b, the top Figs. 1 and 2 are of the flushface kind but may be made of a different form as will later appear.

Spaced a suitable distance from the rear and top edges of the casing is a pin or screw 9 upon which the major parts of the switch are mpunted. /Fulcrumed on said pin is a bell crank shaped contact lever including a long arm 10 and a shorter arm 11. The long ,arm extends toward the bottom of the casing and includes spaced side members -10- 10 (only one of which is shown herein) and between said side members are cross bars 12 in which a laminated contact member 13 `is securely' clamped. Strips let- 14 are of suitable material and are interposed between said contact member and the said cross bars to insulate them. When the contact lever is in one position, the contact 13 bridges the gap between the fixed blocks 7 and 8 and due to its laminated form, said contact bears with a good contacting pressure thereon.

Each side member 10a of the contact lever includes at its bottom end a forward extension 10b which limits the movement Aof the Contact Ylever away from the contacts 74 and 8 by engaging that portion of the insulating material 4 on the front wall 3 of the casing. It is ap arent from the foregoing that an insulate contact chamber is thus provided at said end of the casing. v

The shorter arm 11 of the bell crank contact lever 4includes side plates or members .11-11 and in the forward' end of eacli plate and opening through the same is a and bottom edges or of which provide oppose stop shoulders `a purpose later to appear. The bell crank contact lever includes a rear wall 15 with which the side plates or members of both arms of the lever are integrally mad 16 indicates as a whole the main actuating hand lever or trigger which includes spaced side plates or member 16-16, fulcrumed attheir rear ends upon the pin 9, the front ends of said plates merging into a handle lor actuating trigger 17. Said trigger projects through a suitable slot 3* provlded therefor in the front wall 3 of the casin When the actuating lever isin place, its si e plates or members 16* are interposedlbetween the side plates 11 of the shorter arm o--the bell crank lever and theside walls 2 -2 of the casing as best shown 1n Fig. 3. The

I lever so that it snaps or jumps toward and the tulcrum pin and abutmentblock.

. the recesses 11".

away Jfrom the fixed contacts 7 and 8 according to the direction of movement of the actuating lever. Suchv means are as :tollows r-lExtending between the iront ends ci the side plates or members 1oa of the operating hand lever or trigger is a ulcrum pin 18 and pivoted at one end thereto is a second or toggle pin or spring supporting member 19. The tree or other end oi the toggle pin 19 has a sliding guiding bearing in an abutment block 20, a helical expansion spring 21 surrounding said toggle pin 19 betwepn 'l ie block 20` has laterally extending trunnions 22-22 which pass through suitable openings in the iront end of the side members 23-23 of a toggle arm 24, the said side members being positioned between the side plates 11El of the short arm 11 of the contact lever. rlhe rear end of said toggle arm is provided with one or more extensions 24a which extend through and have aA substantially loose nt in openings in the rear wall 15 ot the Contact lever so as to be capable ci a limited swinging orroclring movement thereabout. The said trun'nions 22 of the block 20 project beyond said side members of the *ulcrum arm to extend into the recesses 1].b of the short arm of the contact leverso as to engage the opposed shoulders formed by the top and.

bottom edges of Vsaid recesses.

The toggle arm 24, the toggle pin or member 19 and the spring 21 together constitute a conventional spring-held toggle lever, the middle portion of which is arranged (in this instance via the trunnions 22) to enga e the stop formations constituted by the wa ls of It will be observed that said stop walls are disposed substantially'radially or the pivotal axis of the switch lever 10 and are so widely spaced apart with reterence to the diameter of the trunnions 22 as to permit of a ver considerable swing of the latter between said stops.

It will also be noted that the pivotal axis of the toggle arm 2t is offset laterali from the common pivotal axis of the switc lever 10 and the hand lever 17 in a direction sub stantially perpendicular to the radial lane of the last-named axis which passes mi way between the stop-formations of the recesses 11".

Assume that the parts are in the position shown in Fig. 1 when the switch is open Leanser the recesses 11b inthe short arm ot the contact lever. The compression action on the spring is increased until the pins 9 and 18 and trunnions 22 are all in a common plane or line and as the pin 18 passes through said plane under the further upward movement of the. actuating lever 16, the toggle eect is broken and the expansion of the spring thus .released causes the toggle arm to swing downwardly about its connection with the rear wall 15 of the Contact arm. ln this movement of the toggle arm 24, the lateral extensions or trunnions 22 will forcefully engage the shoulders formed by the bottom edges of the recesses 11b and will cause the Contact lever to swing clockwise so that the laminated Contact 13 on the bottom end thereof will engage with good contacting pressure against the fixed contacts 7 and e inthe insulation block 5, thus bridging said contacts and closing the circuit therethrough as best shown in Fig. 2. To again open the switch, the lever 16 is swung in the other direction and the parte again operate as be fore describedr Particular attention is directed to the fact that at the moment that the axis ot the spring 21 passes the 'so-called dead-center plane, the block 20 is thrown from one wall or the recesses llbto the other wall thereoie to thereby eect an instantaneous shitting of the said spring axis to such an angle rela tively to the arms 1la oi the switch lever 11 as to exert substantially its iull force on the latter to eect quick action especially where, as in the case or the knife-blade switch ot Fig. d, the movement of the switch lever is frictionally resisted. lt is for this reason that the width oi the recesses 1lb is considerable as shown. The Jfurther eect of the wide spacing of the stops (which the opposed walls of the recesses 11b constitute) is to provide for a relatively long initial movement of the toggle lever between engagements with opposed stops, this long movement being under constantly increasing momentum to thereby eli'ect a hammer blow on `the stop to be engaged. This sharp hammer blow is directed so sharply laterally of the radius of swing of the switch lever as to ailord substantially maximum leverage or pressure to be suddenly exerted on the switch lever to eectually throw the same from one position'to another against such resistance as may be required to be overcome, as in the case of knife-switch contacts.

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l, the spring than the ln ed'ecting closing mevementofl the switch lever, a lesser degree of force is required because of the fact that the switch lever will have attained high. momentum before the instant of its initialcontact with'the knife` switch contacts and thus 'momentum will serve to @dect the requisite depth of engage ment. By the particular arrangement shown, viz: the pivotalassociation of the toggle lever with the switch lever, or, more broadly, the offsetting ofthe pivotal axis of thetoggle lever from that of the switch lever, the diderence of directionsv of pressure of the spring is elfected and adjusted to a nicety. rllhis may be also expressed in terms of and accomplished by other means for Vvarying the direction of pressure of particular means herein shownand described.

lnsome instances it is desirable'that the switch be so made as te he necessarily held in its'closed position manually and that it open automaticall as soon as the handle or trigger is release Such a structure is desired in electrically operated tools as, for

instance, hammers, drills and bonesaws and the like. To hold the switch normally open when the trigger' is released, I employ a helical tension spring which is fixed at its top end lto the lever 16 and at its bottom end to an ear 26 punched out from the bottom end of the front. wall of the casing. rlChns when the lever or trigger 17 is actuated to close the switch, the spring25 is placed under tension which, when the trigger is released, is sufficient to swing the trigger downward even a ainst the resistance odered by the action o the spring 2l.

instead of the laminated and block contacts above described, l may employ the ing between the contacts with theusual burning thereof to a minimum.

llthile in describing my invention, I have referred in detail to the construction for and `arrangement of the parts thereof, the

same is to be talren as by way of illustration only and not by .way of limitation except as may be pointed out in the appended claims.

l claim as my invention:

l. ein electrical snap swi frame equipped with a pair of terminals, a switch lever for the latter ivotally mounted on said frame, a han lever pivotally mounted on said frame, a spring held toggle tch comprising la.v

lever pivotally associated at its ends with said switch lever and said hand-lever, a pairl of spaced stop formations 'on Said switch both levers pivotally mounted on said frame and having a common pivotal a-Xis,.a spring held toggle lever pivotally associated at its ends with said switch lever and said handlever,'a pair of spaced stop formations onv said switch lever disposed for alternate en.- 'gagement by the middle portion of said toggle lever and disposed upon opposite sides of a radius of the pivotal axis of -said switch lever, the pivotal axis of said toggle lever on said switch lever being disposed laterally of said radius. l.

3. An electrical snap switch comprising a frame equipped with a pair of terminals, a bell-crank switch lever pivoted at` its elbow to said, frame, a hand-lever having its. pivotal axis coincident with said switch lever, a

spring held toggle leverpivotally connected at its ends with said hand-lever and with one arm of said switch lever between the pivotof the latter and the end thereof for`bridg ing said terminals, and a pair'of spaced stopy formations at the free end portions of the other arm of said'. switch -lever disposed in the path of the middle portion of said toggle lever.

t. An electrical snap switch comprising a frame equipped with a 'pai'rof terminals, a' switch lever pivoted' between its ends to said frame for bridging said terminals at one end, the other end of said lever equipped with spaced stop formations, a'hand-lever ivoted to said frame and adapted to rock t rough an arc opposed to said stop formations, a spring held toggle lever pivotally associated at its ends with both said levers and adapted to alternately engage said stop 4formations at its middle portion, the pivotal axis 'of the end of said togglelever associated-with the switch lever being offset laterally from the pivotal axis of said hand-lever.

An electrical snap switch comprising a frame equipped with a pair ofterminals, three levers operatively pivotally assoclated with said frame and with eachother, one' thereof being a-switch lever equipped with a pair of spaced stop formations, another being a hand-lever and the third a spring held toggle lever arranged to alternately engage said stop formations at its elbow portion, the

ivotal axis ofene end of said toggle lever being odset frere the pivotal axis o at least one of the other levers laterally oi. the lon gitudinal exis of the latter which intersectsv the pivotal axis of its connection With'the frame.

` 6. An electrical switch embodying therein 5 'a casing open at its ends and having side Walls and e, front Well, a block of insulation partly closing the rear of the casing, iiXed contacts in said block` of insulation, a fulcrum pin journalled in theiside `Wells of the l0 casing,` a bell crank shaped Contact lever pivoted on said pinv and including a, long' arm and a short arm, a Contact member carried by the long arm and adapted to engage and bridge the fixed contact members, there be- 15 ing'ineans on said long arm adapted toengage the ront Wall of the casing and to limitY its movement away from the fixed contacts,

memos ing extensions which project laterally into recesses inthe short arm of the contact lever and which recesses provide opposed shoulders limiting the movement. 'of the toggle arm.

ln testimony whereof, l have hereunto l set my hand7 this 3rd day of March, 1926.

WlLLlAll/ FRANKLNWELLS. i 

